The theory of small world network as initiated by Watts and Strogatz 1998 has drawn new insights on spatial analysis as well as to systems theory. Its concepts and methods are particularly relevant to geography where spatial interaction is mainstream, and where interactions can be described and studied using large volume of exchanges or similarity matrices. Networks indeed organize through direct links or by indirect paths, inducing topological proximities simultaneously involving spatial, social, cultural or organizational dimensions. Network synergies build over similarities and are fed by complementarities between or inside cities, the two effects potentially amplifying each other according to the "preferential attachment" hypothesis that has been explored in a number of different scientific fields (Barabàsi & Albert, 1999; Barabàsi, 2002; Newmann et al., 2006). In fact, according to Barabási & Albert (1999), the high level of hierarchy observed in "scale-free networks" results from "preferential attachment" which characterizes the development of networks: new connections appear preferentially close nodes already having the largest number of connections. In this way, the improvement in the network accessibility of the new connection will probably be greater. But at the same time, network regions gathering dense and numerous weak links (Granovetter, 1973, 1985) or network entities acting as bridges between several components (Burt, 2004) offer a higher capacity for urban communities to benefit from opportunities and create future synergies. Several methodologies have been suggested on how such denser and more coherent regions (also called communities or clusters) in term of links can be identified (Watts & Strogatz, 1998; Watts, 1999; Barabasi & Albert, 2000; Barabasi, 2003; Auber et al. 2003, Newmann et al., 2006). These communities not only possess a high level of dependency between their member entities, but also show a low level of "vulnerability" allowing for numerous redundancies (Burt, 2000, 2005). The SPANGEO project 2005-2008 (SPAtial Networks in GEOgraphy), gathering a team of geographers and computer scientists, has conducted empirical studies to survey concepts and measures developed in other related fields such as physics, sociology or communication science. The relevancy and potential interpretation of weighted or non weighted measures on edges and nodes were examined and analyzed at different scales (intra-urban, inter-urban or both). New classification and clustering schemes based on the relative local density of subgraphs were developed. The article describes how these notions and methods bring a contribution on a conceptual level, in terms of measures, delineations, explanatory analysis and visualization of geographical phenomena. It is shown that, in order to deal in a rigorous way with qualitative information, we can try many tricks. In some cases, the large memories and the power of computation of the machine are enough for facing problems with qualitative data, otherwise non treatable; in other cases, this goal is reached by the possibility of "visualization" of information or "cooperative solution" (through communication) allowed by the computer. Moreover, in some cases the qualitative is managed by means of algorithms (carrying out a sequence of "logical" statements); in other cases the problem is "hardened" (made quantitative), then the output is "relaxed" (reduced to a probabilistic result). Even if the set of methods is rapidly increasing, we look for a taxonomy of the bulk of tools, according to potential use in geography and planning. Considering, for instance, characterization of geographical objects, spatial statistical analysis, territorial modeling and simulation, etc., every qualitative method (e.g. conceptual maps, ontologies, folksonomies, cladistics, qualitative regression, cross impact analysis, expert systems, etc.) is classified, with a short description of its main features. For a better understanding of meaning, procedures and potentialities of qualitative methods, a brief account of four case-studies is given. A software for building "ontology" is used to map a system of interacting agents; "textual statistics" are applied for analyzing the perception of landscape on the basis of an "open answer" (qualitative) survey; the "cross impact analysis" is the qualitative modeling tool built for the evaluation of the consequences of a land-use project; in a qualitative "multi-criteria evaluation" it is grounded the site selection for location of a big infrastructure. As a conclusion, the perspectives of qualitative methods are discussed, in the light of two emerging phenomena: respectively, the incoming "extreme data" availability age; and the next "highly automatic" computer-based research activity epoch.